I've got my plasma above my mantle, not a problem with height for me, but then my sofa is at the other side of the room, a good few meters away. Also got a wall mount with two sections so the angle can be altered (have it set at the minimum right now and is perfect).
Just in case anyone is at all interested here is how i mounted it.
this is the wall mount:
http://www.rs100.co.uk/product_info....roducts_id=170. I couldn't recomend it more. Extremely well made and very strong.
I cut a piece of 18mm plywood to the same size as the mount and fixed that to the wall using 10 70x6mm screws right into the studs. Then fixed the back plane of the mount to the plywood using 12 (if i remember correctly) 25x5mm screws in the pre-drilled holes evenly spaced round the frame. Managed to get all this done on my own, which was a bit of a struggle. My dad helped get the tilting plate fixed on then lift the screen into place.
The screen has two vertical metal battons screwed into frame and then just hangs into the mount at the top and bottom. Very clever, simple and works well.